This invention relates to a method for installing an end member into a hollow shaft member for an office equipment, and more particularly a method for installing an end member into a hollow shaft member having sheet feeding rollers or sheet pressing rollers of these devices in regard to the office equipment such as a printer for computer, a copying machine, a word processor and a facsimile machine and the like; an automation teller machine (hereinafter referred to as the xe2x80x9cATMxe2x80x9d) used in a financial organ, office instruments such as an electrical calculating machines and measuring instruments.
In the prior art, although a shaft member for installing sheet feeding rollers or sheet pressing rollers and the like, for example, is used in the aforesaid business instrument or the ATM, electric calculating machines and measuring instrument and the like, it is general that as the shaft member, a solid member is used.
However, such a solid member had some disadvantages that not only its weight became heavy, but also its manufacturing process became quite complicated and a product cost became high.
Further, in the case that the shaft member was provided with members such as sheet feeding rollers or sheet pressing rollers, the sheet feeding rollers and the shaft member had to be provided with fitting female threads, male threads had to be threadably engaged with and connected to the female threads, and an accurate positioning of these members was required, resulting in that its manufacturing stage was complicated.
In view of the foregoing, the present applicant made a proposal to use the hollow shaft for eliminating these problems. However, in order to fill the hollow part, the end section has to be provided with a solid end member (refer to FIG. 8).
As its installing method in the prior art, the worker had selected only the following methods, i.e. (1) an inner diameter of an aluminum pipe was machined by a lathe to such a size as one in which it could be press-fitted and the pressing member was press-fitted with a precision in press-fitting being increased; (2) or in the case that a high press-fitting strength was needed, adhesive agent was applied to it; or (3) parallel pins or the like were driven in vertical holes formed in the pipe and the end member, or (4) a welding by a frictional pressure welding process was applied to connect these members.
However, in such a method as above, even if the hard end member was press-fitted to the cylindrical aluminum pipe, its precision degree was hardly attained due to soft characteristic of the aluminum pipe and a degree of coaxiality setting the position of the axial center was hardly set in an accurate manner. Further, if the precision was tried to be set, it had to pass through the troublesome and high cost processing step.
Further, the processes such as press-fitting or frictional pressure welding and the like required high energy, their devices were expensive and their energy consumption was severe.
The present invention has been invented to eliminate such disadvantages as above and it is an object of the present invention to develop a method in which both a high degree of coaxiality and a high degree of vertical state can be attained, their steps are simple and they can be realized by a less-expensive cost.
A method for installing an end member into a hollow shaft member comprising the steps of:
(1) using a cylindrical hollow shaft member made of soft metal;
(2) inserting a column-like end member made of hard metal which can be inserted into the hollow shaft member in close contacted state and is formed with a fitting groove satisfying the following requirements (a) to (c),
(a) that the groove is formed at a predetermined position spaced apart from the terminal end of the end member such that the groove may be present along the outer circumferential surface of the end member and become coaxial with an axis of the end member;
(b) that the depth of the groove is set to a suitable depth in which at least an anchoring effect caused by driving action can be attained, the shaft member can reach the bottom surface through driving action and a coaxiality can be attained with a resistance force; and
(c) that the bottom surface of the groove has a sufficient finished precision for attaining a required degree of coaxiality; and
(3) preparing a molding machine having a round hole with a hole diameter not to expand an outer shape of the shaft member in an outward direction at the central part of split dies when a resistance force is generated inside by a pressing member and having at least three pressing members arranged slidably toward the center of the round hole; and
(4) installing the shaft member and the end member in the dies of said molding machine, moving the pressing members toward the center of the round hole, deforming in plastic manner the shaft member with the pressing force of the pressing members toward the fitting groove of the end member to install the end member into the shaft member.
In accordance with the aforesaid configuration, the present invention can provide the following superior effects.
(1) that a plastic deformation of the shaft member into the fitting groove of the end member can be fed by the pressing members to enable a strong anchoring effect to be attained and the deformation is made uniform with relative resistance forces in three directions or more, resulting in that the end member can be fixed to the central position and a high degree of coaxiality can be realized;
(2) that the degree of coaxiality can be realized in high precision due to the fact that a precision in size is determined by the bottom surface of the fitting groove of the end member made of hard material and the inner wall surface of the round hole; and
(3) that a precision is required only at the bottom surface of the fitting groove of the end member of which minute precise machining can be carried out, no precision is required into the shaft member and the like, the end member can be easily installed into the shaft member through a pressing work by the molding die, resulting in that a labor saving can be realized and concurrently it can be manufactured with its cost being less expensive.
(4) In the case of manufacturing the shaft member, it is possible to eliminate a last drawing work with a die formed with a circular hole therein and in particular when two or more rows of the fitting grooves are set in the end member, its remarkable effect can be attained and a substantial labor saving can be provided.